1. Technical Field
The present invention relates to an image forming apparatus including an image forming unit and a pedestal unit, in which the image forming unit is placed in position on the pedestal unit.
2. Related Art
Image forming apparatuses such as a printer, a copier, and a multifunction printer can be found, for example, in JP-A-2002-258562 (see paragraphs [0005] to
and FIGS. 1, 3, 4, and FIG. 6), JP-A-2002-332127 (see paragraphs [0007] to [0009] and FIG. 1), and JP-A-10-226431 (see paragraph [0005] and FIG. 1). The image forming apparatuses disclosed in these documents include an image forming unit having an image forming function, for example a printing function, placed on a pedestal unit serving as a support base. The image forming apparatuses include a positioning mechanism for setting the image forming unit in position on the pedestal unit.
For example, the image forming apparatus according to JP-A-2002-258562 includes a positioning mechanism including a positioning pin (positioning projection) located on an upper face of an option such as a paper bank (pedestal unit) additionally provided under the image forming apparatus main body, and a positioning hole (positioning recess) provided on a bottom face of the image forming apparatus main body. Upon engaging the positioning pin with the positioning hole, the position of the image forming apparatus main body with respect to the option is determined in left-right and front-back directions.
According to JP-A-2002-332127, the image forming apparatus main body includes a circular hole and an elliptical hole to be engaged with a longer and a shorter pin projecting from an upper face of an additional unit (for example a paper feed unit) provided under the image forming apparatus main body.
Further, according to JP-A-10-226431 the upper unit includes a caster and a vertically retractable positioning pin provided on a bottom plate of the upper unit, and the lower unit includes a positioning hole provided on a top plate of the lower unit. Upon fitting the positioning pin in the positioning hole, the upper unit is properly positioned with respect to the lower unit. The positioning pin is biased in the projecting direction by a spring, and when the positioning is achieved the caster is fitted in a recessed portion formed on the top plate of the lower unit, thus to settle in the recessed portion.
Now, in case that, when the image forming unit is to be mounted on the pedestal unit, the positioning projection of the pedestal unit is not properly fitted in the positioning recess of the image forming unit and the image forming unit is tilted with the mounting surface thereof disposed in contact with the positioning projection, so that the center of gravity is shifted to the tilted side, the tilted image forming unit may be relatively displaced (slip) with respect to the pedestal unit. If the image forming unit is largely shifted with respect to the pedestal unit in such a case, it requires a great effort to bring the shifted image forming unit back to the correct position where the image forming unit is supposed to be.